**Etymology and Classification**:
– The English word ‘fungus’ originates from the Latin ‘fungus’ and the Greek ‘sphongos’ (σφόγγος sponge).
– Fungi are eukaryotic organisms with chitin in their cell walls.
– They are classified in the kingdom Fungi along with yeasts, molds, and mushrooms.
– Fungi are heterotrophs that absorb dissolved molecules and are principal decomposers in ecosystems.
– Fungi do not photosynthesize and are genetically closer to animals than plants.
**Ecological Importance and Biodiversity**:
– Fungi play essential roles in decomposition and nutrient cycling.
– They are used in food production like mushrooms, truffles, and fermentation.
– Fungi are sources of antibiotics and industrial enzymes.
– Some fungi produce toxic compounds harmful to animals, including humans, and can be pathogens of humans, animals, and crops.
– The fungi kingdom has an estimated 2.2 to 3.8 million species, with only about 148,000 species described.
**Historical Perspective and Mycology**:
– Fungi were historically classified with plants but are now recognized as a separate kingdom.
– Fungi share features with eukaryotes, animals, and plants and reproduce sexually and asexually.
– Mycology is the branch of biology focused on the study of fungi, including their genetic, biochemical, and taxonomic properties.
– Humans have used fungi for various purposes throughout history, such as for medicine, food, and religious practices.
– Ötzi the Iceman, a 5,300-year-old mummy, carried polypore mushrooms, possibly for medicinal or other purposes.
**Taxonomy and Morphology**:
– The taxonomy of fungi has evolved from morphology-based to DNA-based classification.
– Fungi have a worldwide distribution and grow in various habitats, including extreme environments.
– Most fungi grow as hyphae, which are cylindrical, thread-like structures with various microscopic structures like conidiophores and septa.
– Fungal mycelia can be visible on surfaces like walls and spoiled food, known as molds, with unique shapes and colors for species identification.
– Fungi secrete hydrolytic enzymes to digest organic molecules for nutrient absorption.
**Reproduction and Evolution**:
– Fungi have complex reproduction methods involving sexual and asexual stages, with specialized structures aiding in spore dispersal.
– Sexual reproduction with meiosis is observed in all fungal phyla except Glomeromycota.
– Fossil records of fungi date back to around 2,400 million years ago, with challenges in distinguishing fungal fossils from other microbes.
– Homothallic reproduction involves fusion of haploid nuclei from the same individual, with examples in various fungal genera.
– Spore dispersal in fungi occurs through various mechanisms like wind dispersal, raindrop scattering, and active ejection from reproductive structures.
A fungus (pl.: fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as one of the traditional eukaryotic kingdoms, along with Animalia, Plantae and either Protista or Protozoa and Chromista.
| Fungi | |
|---|---|
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Clockwise from top left:
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Scientific classification 
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| Domain: | Eukaryota |
| Clade: | Obazoa |
| (unranked): | Opisthokonta |
| Clade: | Holomycota |
| Kingdom: | Fungi (L.) R.T.Moore |
| Subkingdoms/Phyla | |
A characteristic that places fungi in a different kingdom from plants, bacteria, and some protists is chitin in their cell walls. Fungi, like animals, are heterotrophs; they acquire their food by absorbing dissolved molecules, typically by secreting digestive enzymes into their environment. Fungi do not photosynthesize. Growth is their means of mobility, except for spores (a few of which are flagellated), which may travel through the air or water. Fungi are the principal decomposers in ecological systems. These and other differences place fungi in a single group of related organisms, named the Eumycota (true fungi or Eumycetes), that share a common ancestor (i.e. they form a monophyletic group), an interpretation that is also strongly supported by molecular phylogenetics. This fungal group is distinct from the structurally similar myxomycetes (slime molds) and oomycetes (water molds). The discipline of biology devoted to the study of fungi is known as mycology (from the Greek μύκης mykes, mushroom). In the past mycology was regarded as a branch of botany, although it is now known that fungi are genetically more closely related to animals than to plants.
Abundant worldwide, most fungi are inconspicuous because of the small size of their structures, and their cryptic lifestyles in soil or on dead matter. Fungi include symbionts of plants, animals, or other fungi and also parasites. They may become noticeable when fruiting, either as mushrooms or as molds. Fungi perform an essential role in the decomposition of organic matter and have fundamental roles in nutrient cycling and exchange in the environment. They have long been used as a direct source of human food, in the form of mushrooms and truffles; as a leavening agent for bread; and in the fermentation of various food products, such as wine, beer, and soy sauce. Since the 1940s, fungi have been used for the production of antibiotics, and, more recently, various enzymes produced by fungi are used industrially and in detergents. Fungi are also used as biological pesticides to control weeds, plant diseases, and insect pests. Many species produce bioactive compounds called mycotoxins, such as alkaloids and polyketides, that are toxic to animals, including humans. The fruiting structures of a few species contain psychotropic compounds and are consumed recreationally or in traditional spiritual ceremonies. Fungi can break down manufactured materials and buildings, and become significant pathogens of humans and other animals. Losses of crops due to fungal diseases (e.g., rice blast disease) or food spoilage can have a large impact on human food supplies and local economies.
The fungus kingdom encompasses an enormous diversity of taxa with varied ecologies, life cycle strategies, and morphologies ranging from unicellular aquatic chytrids to large mushrooms. However, little is known of the true biodiversity of the fungus kingdom, which has been estimated at 2.2 million to 3.8 million species. Of these, only about 148,000 have been described, with over 8,000 species known to be detrimental to plants and at least 300 that can be pathogenic to humans. Ever since the pioneering 18th and 19th century taxonomical works of Carl Linnaeus, Christiaan Hendrik Persoon, and Elias Magnus Fries, fungi have been classified according to their morphology (e.g., characteristics such as spore color or microscopic features) or physiology. Advances in molecular genetics have opened the way for DNA analysis to be incorporated into taxonomy, which has sometimes challenged the historical groupings based on morphology and other traits. Phylogenetic studies published in the first decade of the 21st century have helped reshape the classification within the fungi kingdom, which is divided into one subkingdom, seven phyla, and ten subphyla.